`sig
type 'a t
val required : 'a Command.Arg_type.t -> 'a Command.Flag.t
val optional : 'a Command.Arg_type.t -> 'a option Command.Flag.t
val optional_with_default :
'a -> 'a Command.Arg_type.t -> 'a Command.Flag.t
val listed : 'a Command.Arg_type.t -> 'a list Command.Flag.t
val one_or_more : 'a Command.Arg_type.t -> ('a * 'a list) Command.Flag.t
val no_arg : bool Command.Flag.t
val no_arg_register :
key:'a Core_kernel.Std.Univ_map.With_default.Key.t ->
value:'a -> bool Command.Flag.t
val no_arg_abort :
exit:(unit -> Core_kernel.Std.never_returns) -> unit Command.Flag.t
val escape : string list option Command.Flag.t
end`